A DNA polymerase from Geobacillus stearothermophilus has been described in Kong, et al., U.S. Pat. No. 5,814,506 (1998). This enzyme, which is a Bst DNA polymerase belongs to the Family A DNA polymerase and shares about 45% sequence identity with its better known relative Taq DNA polymerase. Whereas Taq DNA polymerase is from a hyperthermophilic organism and is able to survive the high temperatures of the polymerase chain reaction, the Bst DNA polymerase reported in Kong, et al., is from a thermophilic organism, is optimally active between 60-70° C., but does not survive the high temperatures of PCR. The full length (FL) Bst DNA polymerase is 876 amino acid residues and has 5′-3′ endonuclease activity but not 3′-5′ exonuclease activity. The large fragment (LF) of Bst DNA polymerase lacks both 5′-3′ exonuclease activity and 3′-5′ exonuclease activity and is only 587 amino acid residues with 289 amino acids being deleted from the N-terminal end. The full length Bst DNA polymerase and the large fragment Bst DNA polymerase have been found to be useful for isothermal amplification techniques and DNA sequencing.